Removal of nitrogen compounds from heating oil



J y 19 0 H. c. PAULSEN 2,944,063

REMOVAL OF NITROGEN COMPOUNDS FROM HEATING OIL Filed June 17, 1953 93 838.55 fi wwmmm 85828 $852 nu v n B Exm Emfiom ll 5 mm n 35 55 k. R A m T v Smfiom Q3 oEoxmmozm mm III l mm mm H r k H m NN um EH28 25 9 W T V =oQE wE um T LN 5.5,

Que OEOIQMOIQ Henry C. Paulsen Inventor By w- 7WAflorney United States Patent REMOVAL OF NITROGEN COMPOUNDS FROM HEATING OIL Henry C. Paulsen, Elizabeth, N.'.I., assignor. to Esso Research and Engineering Company, a corporation of V Delaware Filed June 17, 1953, Ser. No. 362,197

'3 Claims. c1. rac -31s The present invention is concerned with an improved process for securing high quality heating oils. The invention is more particularly concerned with the removal of nitrogen compounds, particularly of the pyrrole type, from heating oils and the subsequent recovery of these nitrogen compounds. In accordance with the present invention, petroleum oils, particularly heating oils, are treated with an acid of phosphorous to remove the nitrogen compounds which compounds are subsequently recovered from the acids of phosphorous utilizing a halogenated solvent.

As mentioned, the present invention is concerned with the production of high quality fuel oils. These fuel oils are produced for use such as domestic heating oils, diesel fuels and the like, and are oils of boiling range similar to kerosene and light gas oil, often derived at least in part from a catalytic cracking operation. These fuel oils are not to be confused with the heavier fuel oils of a residual nature, obtained as a residue from the distillation of crude oil, or as a residue from a cracking operation and the like. These light fuel oils, particularly those derived from catalytic cracking operations contain undesirable nitrogen compounds and are frequently prone to deterioration in storage, possibly due to the mild but prolonged oxidizing conditions of such storage. This deterioration results in the formation of objectionable sludge or sediment, which if not removed plugs filter screens, orifices and other parts of the equipment used for burning such fuel. Even when after some storage all feasible sediment is removed from said oils, other sediment continues to form.

Thus, the present invention is broadly concerned with improved hydrocarbon mixtures known as fuel oils of the nature employed in various burner systems, as diesel fuels, or as domestic and industrial heating oils. The fuel oils of the present invention are generally derived from petroleum by a variety of methods including straight distillation from crude petroleum oil, and thermal or catalytic cracking of various petroleum oil fractions.

As pointed out, it has been found that fuel oils, particularly those consisting completely or in part of catalytic cracked stocks are characterized by an undesirable instability giving rise to the formation of sediment. As a result, such fuel oils tend to cause clogging of filters, orifices, or conduits associated with the burning systems in which they are employed. Heating oils which may be eifectively stabilized by the addition of the present invention are particularly hydrocarbon mixtures of which more than about preferably more than about 20% consist of stocks derived from catalytic cracking operations. More precisely still, the base stocks may be characterized as petroleum fractions containing a proportion of catalytic cracked stocks greater than 10%, preferably greater than 20% and falling within A.S.T.M. Specification D-975-48T for diesel fuel oils (grade Nos. 1-D, 2-D and 4-D) and A.S.T.M. Specification D-39648T for fuel oils (grade Nos. 1 to 6 inclusive).

To enable understanding of this invention, there is first ice defined the type of fuel; oil with which it is concerned, by way of the following example, showing properties of atypical. #3 fuel oil:

UNTREATED #3 FUEL. 01L

Gravity, A.P.I. V 34.0

Distillation, A.S.T.M.

1 B.P., F. 342

5 B.P., F. 405

10- B.P., F. V 417 20 B.P., F. V 434 B.P., F 444 50 B.P., F. 464

60' B.P., F. 473

80 B.P., F. 4.94

Recovery percent V V V V 98 Residue percent Z Loss percent V V V (1 Pour point, F. ,V 30,

Flash point P.M., F. ..V 15,6

' Kinematic visc. 100 F. 1.98

Aniline cloud point, F. V .V. 112.0,

Kauri-butanol No. V V 43.5

Neutralization No. V 0.07

While the above oil is an untreated oil, many of these, oils are treated, that is, have been treated for example with 5 pounds per barrel of 66 B. sulfuric acid, followed by water washing and neutralizing. This treating has little effect upon physical properties, but serves to reduce the tendency of sludging, sediment formation, etc.

As pointed out heretofore, a specific adaptation of the invention is to recover these ring structured nitrogen compounds from oils particularly cracked heating oils. The process of the present invention may be more fully appreciated by reference to the drawing illustrating one embodiment of the same. Referring specifically to the drawing a feed oil which comprises aheating oil containing cracked constituents is introduced into contacting zone 1 by means of feed line 2. Phosphoric acid isintroduced into zone 1 by means of line 3. In operation a pump around system is employed which comprises withdrawing a portion of the oil and acid by means of lines 4 and 13, pumping this stream by means of pump 5 through heat exchange unit 6 back into zone 1. The treated oil, after a settling period, is removed by means of line 7 and mixed with water by means of line 8. The oil and water is thoroughly mixed in mixing unit 9 and introduced into settling zone 10. The wash water containing small traces of phosphoric acid is removed by means of line 11 while the treated oil is removed by means of line 12.

Spent acid is removed from zone 1 by means of line 13, mixed with water which is added by means of line 14. This acid-water phase is passed through a mixing zone 15 and stored in storage zone 16.

The dilute acid phase is removed from storage zone 16 by means of line 17 and mixed with a solvent such as chloroform which is introduced by means of line 18. The solvent-dilute acid phase is passed through a mixing zone 19 and into a storage zone 20. The acid phase is removed from zone 20 by means of line 21 and mixed with additional solvent introduced by means of line 22. This solvent acid phase is passed through a mixing zone 23 and introduced into a settling zone 24.

The acid phase is removed from zone 24 by means of line 25 and passed into a distillation zone 26. Temperature and pressure conditions in zone 26 are adapted to the nitrogen compounds.

remove overhead by means of line 27 the water and to remove by means of line 28 concentrated phosphoric acid.

The solvent extract is withdrawn hrom zone 20 by means of line 29 and from'zone 24 by means of line 30. These streams are" passed to distillation zone 31 by means of line 32. Temperature and pressure conditions in zone 31 are adapted to remove overhead by meansof line 33 the solvent and to recover by means of line 34 These pyrroles may be further refined and purified by distillation of the recovered crude traction. However, the preferred method is to convert the pyrroles into the potassium compound (C H NK). The potassium compound is then washed with ether, then treated with water, dried and distilled to secure the desired fraction.

The invention essentially comprises the production of improved petroleum products, particularly heating oils. The invention 'is' more specifically concerned with the 1. The process of recovering cyclic nitrogen com- 5. pounds from mineral oils boiling in the heating oil boilrecovery of nitrogen compounds. This is secured by treatin'g'the oil with an acid of phosphorous having a concentration in the range from about 80 to 95%. A preferred concentration is in the range from about 83 to The amount of acid used will vary depending upon various factors but is preferably in the range from about 3 to 15% by volume. A preferred quantity is in the range from about to of the acid based upon the volume of oil. Temperatures of contacting should be in the range from 80 to 160 5.; preferred temperatures arein the range from 100 to 130 F.

. The spent acid phase withdrawn from the treating zone containing the nitrogen compound is diluted to a concentration less than about 40 weight percent phosphoric acid. A preferred concentration of phosphoric acid is a -30% by weight concentration.

This dilute acid phase is contacted with a halogenated solvent. Particularly desirable solvents comprise chloroform and carbon tetrachloride. Other solvents, as for example highly chlorinated hydrocarbons may be used. The temperature of contacting with the solvent is in the range from 80 to 120 F., preferably in the range from 90 to 100 F. 'The amount of solvent employed will depend upon various conditions butin general two treats of from 5 to 15 volume percent of solvent are used based on the volume of dilute phosphoric acid.

The process of the present invention may be more fully understood by the following example illustrating the same.

Example 1 An untreated cracked'distillate boiling in the heating ing range and containing the same comprising the steps of mixing said mineral oil with about 3% to about 15 by volume of an acid of phosphorus having an acid concentration of -95% by weight, segregating the mixture of oil and acid so formed into an oil phase and a spent acid pliase,'mixing said spent acid phase with sufiicient water to form a dilute acid phase containing less than about 40% by weight of acid, mixing said dilute acid phase with a chlorinated solvent selected from the group consisting of chloroform and carbon tetrachloride to form a second acid phase and a solvent phase, segre gating said second acid phase from said solvent phase and recovering said cyclic nitrogen compounds from said solvent phase. 7

2. The process according to claim 1 wherein said mineral oil and said acid are contacted While at a temperature in the range of F. to F.

3. The process according to claim 2 wherein the spent acid phase is mixed with sufiicient 'water to form a dilute acid phase containing from 20% to 30% by weight of acid.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Jour. Am. Chem. Soc., vol. 73, pp. 4040-41 (1951). 

1. THE PROCESS OF RECOVERING CYCLIC NITROGEN COMPOUNDS FROM MINERAL OILS BOILING IN THE HEATI NG OIL BOILING RANGE AND CONTAINING THE SAME COMPRISING THE STEPS OF MIXING SAID MINERAL OIL WITH ABOUT 3% TO ABOUT 15% BY VOLUME OF AN ACID OF PHOSPHORUS HAVING AN ACID CONCENTRATION OF 80-95% BY WEIGHT, SEGREGATING THE MIXTURE OF OIL AND ACID SO FORMED I NTO AN OIL PHASE AND A SPENT ACID PHASE, MIXING SAID SPENT ACID PHASE WITH SUFFICIENT WATER TO FORM A DILUTE ACID PHASE CONTAINING LESS THAN ABOUT 40% BY WEIGHT OF ACID, MIXING SAID DILUTE ACID PHASE WITH A CHLORINATED SOLVENT SELECTED FROM THE GROUP CONSISTING OF CHLOROFORM AND CARBON TETRACHLORIDE TO FORM A SECOND ACID PHASE AND A SOLVENT PHASE, SEGREGATING SAID SECOND ACID PHASE FROM SAID SOLVENT PHASE AND RECOVERING SAID CYCLIC NITROGEN COMPOUNDS FROM SAID SOLVENT PHASE. 